3641 results about "Amplitude modulation" patented technology

An electrosurgical system has an electrosurgical generator and a bipolar electrosurgical instrument, the generator being arranged to perform a treatment cycle in which radio frequency energy is delivered to the instrument as an amplitude-modulated radio frequency power signal in the form of a succession of pulses characterized by successive pulses of progressively increasing pulse width and progressively decreasing pulse amplitude. There are periods of at least 100 milliseconds between successive pulses, and the treatment cycle begins with a predetermined pulse mark-to-space ratio. Energy delivery between pulses is substantially zero. Each burst is of sufficiently high power to form vapor bubbles within tissue being treated and the time between successive pulses is sufficiently long to permit condensation of the vapor.

An electrosurgical system has an electrosurgical generator and a bipolar electrosurgical instrument, the generator being arranged to perform a treatment cycle in which radio frequency energy is delivered to the instrument as an amplitude-modulated radio frequency power signal in the form of a succession of pulses characterized by periods of a least 100 milliseconds between successive pulses and by a predetermined pulse mark-to-space ratio. Energy delivery between pulses is substantially zero and the mark-to-space ratio is typically 1:4 or less. Each burst is of sufficiently high power to form vapor bubbles within tissue being treated and the time between successive pulses is sufficiently long to permit condensation of the vapor. The treatment cycles may each include an initial period and a subsequent period, the pulse duty cycle being increased or energy being delivered continuously in the subsequent period in order that tissue coagulation can be achieved quickly despite increasing tissue impedance.

A novel apparatus and method of improving the power efficiency of a digital transmitter for non-constant-amplitude modulation schemes. The power efficiency improvement mechanism of the invention leverages the high efficiency of a switched-mode power supply (SMPS) that supplies the high DC current to the transmitter's power amplifier, while compensating for its limitations using predistortion. The predistortion may be achieved using any suitable technique such as digital signal processing, hardware techniques, etc. A switched mode power supply (i.e. switching regulator) is used to provide a slow form (i.e. reduced bandwidth) of envelope tracking (based on a narrower bandwidth distorted version of the envelope waveform) such that the switching regulator can use a lower switching rate corresponding to the lower bandwidth, thereby obtaining high efficiency in the switching regulator. The resulting AM-AM and AM-PM distortions in the power amplifier are compensated through predistortion of the digital amplitude modulating signal which dictates the envelope at the PA input. Similarly, the phase modulation is also compensated prior to the PA, such that once it undergoes the distortion in the PA, the end result is sufficiently close to the desired phase.

One embodiment includes a sputtering system that includes a vacuum chamber; a substrate transport system configured to transport a substrate through the vacuum chamber; a cathode for supporting a sputtering target, the cathode at least partially inside the vacuum chamber; and a power supply configured to supply power to the cathode and the power supply configured to output a modulated power signal. Depending upon the implementation, the power supply can be configured to output an amplitude-modulated power signal; a frequency-modulated power signal; a pulse-width power signal; a pulse-position power signal; a pulse-amplitude modulated power signal; or any other type of modulated power or energy signal.

An amplifier system is provided that switches between a linear mode of operation, an envelope tracking mode of operation and a polar mode of operation. The amplifier system switches between modes of operation based upon a characteristic of an input signal relative to a first threshold level and a second threshold level. A mode selector selects the operation mode by transmitting an amplitude modulated signal plus a variable headroom voltage to a supply terminal of a power amplifier during the envelope tracking mode, an amplitude modulated signal to the supply terminal and phase modulated input signal during the polar mode and a substantially constant amplitude signal to the supply terminal during the linear mode.

The invention discloses a multi-dimensional encryption anti-counterfeiting printing technology based on binary signals. According to the anti-counterfeiting printing technology, two-dimensional encryption anti-counterfeiting information can be generated into binary modulation signals by encryption and channel coding, and the anti-counterfeiting information is orderly changed in an amplitude modulation screening form and embedded into a whole page in a modulation mode of a circulating table look-up method, so that the anti-counterfeiting information can be identified from a random fragment during presswork identification. The technology has strong fragment resistance, can resist illegal copying behaviors based on a camera, a scanner, an electronic document and the like more effectively, and can be widely applied in the anti-counterfeiting field of presswork.

Apparatus and methods are described that enable concurrent transmission of multiple data signals including clock, synchronization, and power over a single-wire bus between a master device and one or more slave devices. A first transmission channel from the master device to the slave device may modulate the width of periodic pulses between a first voltage level and a second voltage level with respect to a reference potential. A second transmission channel may modulate the amplitude of at least one of the first and second voltage levels to at least one third voltage level. Concurrent communications between a master device and one or more slave devices over a single-wire bus can be achieved.

The invention discloses an encrypting anti-counterfeiting printing technology for modulating the shapes of amplitude modulation dots of a printed work through a binary-system encrypting signal. In the anti-counterfeiting printing technology, anti-counterfeiting information is subjected to encryption and channel coding to form a binary-system modulating signal and the anti-counterfeiting information is embedded into a whole page by sequentially changing the shapes of the amplitude modulation dots in a circulating table lookup modulation way. During recognition of the printed work, the anti-counterfeiting information can be recognized from any fragment, so the anti-breakage performance is high, the illegal replication based on a camera, a scanner, an electronic document and the like can be more effectively prevented and the technology can be extensively applied to the field of printed work anti-counterfeiting.

The present invention provides a method and apparatus of using light-emitting elements for illumination as well as communication of data, wherein potential flicker due to sub-fusion frequency data correlations can be reduced compared to prior art techniques, while reducing redundancy in the data transmission. The intensity of the illumination from the light-emitting elements is controlled by a dimming signal such as a pulse width modulation (PWM) signal or a pulse code modulation (PCM) signal, for example. An amplitude-modulated data signal is then superimposed on the dimming signal for communication of data. The dimming signal thus acts as a carrier signal for the data signal. A sensing means is then used to receive the data signal by detecting all or part of the illumination from the light-emitting elements. The data signal can subsequently be extracted from the detected illumination.

One aspect of the present invention is related to a quantum cryptographic scheme comprising at least one sending unit including a physical means of encoding and distributing a raw key in the quadrature components of quantum coherent states that are continuously modulated in phase and amplitude, at least one receiving unit containing a physical means of performing homodyne detection of the quantum coherent states in order to measure the quadrature components of the states, a quantum channel for connecting the sending unit to the receiving unit, a two-way authenticated public channel for transmitting non-secret messages between the sending unit and the receiving unit, a quantum key distribution protocol ensuring that the information tapped by a potential eavesdropper can be estimated from the quantum channel parameters, and a direct or reverse reconciliation protocol that converts the raw continuous data into a common binary key.

An amplifier system is provided that switches between a linear mode of operation, an envelope tracking mode of operation and a polar mode of operation. The amplifier system switches between modes of operation based upon a characteristic of an input signal relative to a first threshold level and a second threshold level. A mode selector selects the operation mode by transmitting an amplitude modulated signal plus a variable headroom voltage to a supply terminal of a power amplifier during the envelope tracking mode, an amplitude modulated signal to the supply terminal and phase modulated input signal during the polar mode and a substantially constant amplitude signal to the supply terminal during the linear mode.

Methods and systems for monitoring contact between a medical probe and tissue are provided. A medical probe is introduced into a patient adjacent the tissue. An electrical parameter, e.g., electrical admittance, is measuring between a first electrode located on the medical probe and a second electrode remote from the first electrode. The electrical parameter is amplitude modulated in response to a physiological cycle of the patient. Contact between the medical probe and the tissue is detected based on the amplitude modulation of the measured electrical parameter.

A holographic waveguide display comprises: a source of light; at least one switchable grating layer comprising a multiplicity of grating regions each switchable between a diffracting state and a non diffracting state; means for spatio-temporally modulating light from the source to provide image light comprising at least one beam deflector for scanning the light in at least one of two orthogonal directions and at least one modulator for amplitude modulating the light. A first scanned angular range of light is diffracted through a first area into a first field of view by a first set of grating regions, and through a second area into to the first field of view by a second set of grating regions. Each grating region of the first and second sets has a first grating function. The first and second areas lie within an exit pupil of the display.

A class of bandwidth reduction techniques are used develop a broad class of modulation types collectively called SSB-FM. These signals can be used to construct communication systems that provide bandwidth-normalized performance gains of 10 dB or more when compared to popular prior art modulation methods. An aspect of the invention involves mapping trellis paths in a complex signal space onto corresponding real-valued trellis signals with desirable spectral properties. The invention can be used map continuous phase modulated (CPM) signals onto simpler amplitude-modulated trellis signals having double the channel capacity of prior art CPM signals. Multi-amplitude signaling and frequency division multiplexing may also be incorporated to further accommodate more information per symbol.

Small portable communication devices that support multiple modulation techniques cannot gain the benefits of using an isolator at the output of a power amplifier to provide stability in the load impedance. However, for communication devices that include amplitude modulation schemes, maintaining linear operation of the power amplifier is still required. In the presence of unstable load impedance, this can be a difficult task. As a solution, the linearity of the power amplifier is detected by determining the peak power of the output signal and the average or root-mean-square of a portion of the output signal, such as a mid-amble). The ratio of the peak power and the average power of the output signal are used to determine if the power amplifier is operating in the linear region. If the ratio is too high, then the power amplifier may be operating in the linear region. By adjusting the power level of the input signal to the power amplifier when the ratio increases, linearity of the power amplifier is maintained.

An amplifier circuit includes a power amplifier biased for saturated mode operation, and a controllable current source to provide supply current to the power amplifier. The controllable current source effects desired amplitude modulation of the output signal from the power amplifier by modulating the supply current it provides responsive to an amplitude information signal. In one or more embodiments, the current source includes a circuit that is configured to adjust one or more transmitter operating parameters responsive to detecting changes in the effective DC resistance of the power amplifier. For example, the circuit may generate a compensation signal that reduces the effective DC resistance responsive to detecting that the effective DC resistance has undesirably increased. By way of non-limiting examples, such compensation may be effected by changing a current mirror, an amplifier-to-antenna impedance matching, an amplifier bias or device size, or imposing some form of transmit signal back-off.

An ultrasonic surgical dissection system and method that employs an ultrasonic waveform that provides improved dissection of tissue while simultaneously providing improved hemostasis is disclosed. The disclosed system provides an ultrasonic waveform that includes a carrier frequency that may be pulse modulated at a predetermined rate and / or duty cycle. Embodiments are presented wherein the disclosed system provides an ultrasonic waveform having a frequency modulated carrier frequency. Additionally or alternatively, the disclosed waveform may be amplitude modulated. In yet another embodiment, an amplitude modulation of the ultrasonic signal may be synchronized, at least in part, with a frequency modulation of the ultrasonic signal. The frequency modulation and / or amplitude modulation may include continuously variable modulations and / or substantially instantaneous transitions between a first frequency and a second frequency and / or a first amplitude and a second amplitude.

A method is provided for an equalization strategy for compensating channel distortions in a dual-polarization optical transport system wherein the received signal includes a complex signal of a first transmitted polarization component and a complex signal of a second transmitted polarization component. In a first step, a blind self-recovery mode used a blind adaptation algorithm in calculating and modifying multiple complex equalizer transfer function coefficients to enable recovery of only the complex signal of the first transmitted polarization component. By recovering only a single polarization component in the first step the degenerate case of recovering only a single transmitted signal at both polarization component outputs of an equalizer is prevented. In a second step, equalization is performed in a training mode for calculating and modifying the multiple complex equalizer transfer function coefficients to enable recovery of the complex signals of the first and second transmitted polarization components. In a third step, equalization is performed in a data directed mode for continuing to calculate and modify the multiple complex equalizer transfer function coefficients to ensure continued recovery of the complex signals of the first and second transmitted polarization components. The method is suited for a digital signal processing implementation in a coherent receiver when a modulation scheme used on a transmitted signal is quadriphase-shift keying (QPSK). In other embodiments, the method can be used with modulation schemes such as binary PSK, M-ary PSK where M>4, or Quadrature Amplitude Modulation (QAM).

Certain aspects of a method and system for a wideband polar transmitter may be disclosed. Aspects of the method may include polar modulating a plurality of signals by generating a plurality of modulated intermediate frequency (IF) signals corresponding to each of a plurality of wireless communication protocols within a transmitter that handles the plurality of wireless communication protocols. The generated plurality of modulated IF signals may be upconverted to a plurality of radio frequency (RF) signals. The plurality of RF signals may be combined and the combined plurality of RF signals may be amplitude modulated.

A fully automated package identification and measuring system, in which an omni-directional holographic scanning tunnel is used to read bar codes on packages entering the tunnel, while a package dimensioning subsystem is used to capture information about the package prior to entry into the tunnel. Mathematical models are created on a real-time basis for the geometry of the package and the position of the laser scanning beam used to read the bar code symbol thereon. The mathematical models are analyzed to determine if collected and queued package identification data is spatially and / or temporally correlated with package measurement data using vector-based ray-tracing methods, homogeneous transformations, and object-oriented decision logic so as to enable simultaneous tracking of multiple packages being transported through the scanning tunnel.

An improved hearing aid, and processes for adaptively processing signals therein to improve the perception of desired sounds by a user thereof. In one broad aspect, the present invention relates to a process in which one or more signal processing methods are applied to frequency band signals derived from an input digital signal. The level of each frequency band signal is computed and compared to at least one plurality of threshold values to determine which signal processing schemes are to be applied. In one embodiment of the invention, each plurality of threshold values to which levels of the frequency band signals are compared, is derived from a speech-shaped spectrum. Additional measures such as amplitude modulation or a signal index may also be employed and compared to corresponding threshold values in the determination.

The present invention provides a method for detecting vibration information by receiving electromagnetic radiation reflected or emitted from a biological organism at a light amplitude modulation detector array to provide real-time imaging of the target object. The detected radiation may be visible light, infrared or ultraviolet radiation, and / or of other desired frequency ranges. The detected radiation is preferably AC-coupled to isolate components relating to oscillations of the biological organism from components relating to ambient radiation, e.g. background sunlight. The isolated oscillations may then be digitized, stored, and subjected to processing such as a Fourier transform to generate outputs representative of frequencies of oscillation. This output can then be used for analysis of the target object.

Apparatuses (e.g., devices, systems), and methods for transdermal electrical stimulation (TES). Apparatuses described herein can be self-contained, lightweight, and wearable. The apparatuses and methods described herein be configured to apply an ensemble current waveform between the two or more electrodes, wherein the ensemble current waveform comprises a series of component waveforms that are sequentially applied, and wherein each component waveform is different from a component waveform immediately before it and wherein transitions between the component waveforms temporally correlates with transitions in the sensory experience. Also described are neurostimulators for application of transdermal electrical stimulation (TES) and methods of using them for comfortably inducing a cognitive effect. Also described are Methods and apparatuses for amplitude modulation of all or a portion of an ensemble waveform to modify a user's cognitive state by transdermal electrical stimulation (TES).

A tape data carrier for protecting articles and documents from counterfeiting and copying is formed by a polymer structure including at least one polymer layer of which at least one layer has at least one of through-perforations and pits. These through-perforations and pits are preferably between 0.001 mum and 20 mum in size and can be filled with different materials. The data carriers can carry concealed and visible macro-and micro- images created by heavy-ion bombardment of the polymer film, subsequent exposure of the bombarded film to ultraviolet radiation, and etching of the polymer film in a solvent. A device for manufacturing a data carrier of this type includes the following elements configured in series: a heavy ion source; a heavy ion beam-formation system; an ion guide; a three-dimensional amplitude modulation unit; and a target which is destined to become the data carrier. The three-dimensional amplitude modulation unit is designed to hold a matrix of wafers and is connected to a drive for rotating and translating the wafers. The drive is connected via a control unit to the three-dimensional amplitude modulation unit for positioning the target.

The amplitude modulator comprises: an angle modulator for angle-modulating a phase signal to be inputted; a waveform shaping means in which, (1) when the magnitude of an amplitude signal to be inputted becomes smaller than a first prescribed value, a waveform of the amplitude signal is shaped so that the magnitude of the amplitude signal of the portion which becomes small becomes the first prescribed value; and / or (2) the waveform shaping means in which, when the magnitude of the amplitude signal to be inputted becomes larger than the second prescribed value which is larger than the first prescribed value, the waveform of the amplitude signal is shaped so that the magnitude of the amplitude signal of the portion which becomes larger becomes the second prescribed value; and an amplitude modulator for amplitude modulating the signal of the output of the angle modulator by the signal of the output of the waveform shaping means.

This invention generally relates to an optical filter for a fiber optic communication system. A coupled multi-cavity optical filter may be used, following a directly modulated laser source, and converts a partially frequency modulated signal into a substantially amplitude modulated signal. The optical filter may compensate for the dispersion in the fiber optic transmission medium and may also lock the wavelength of the laser source.

Exemplary embodiments provide a system, method and apparatus for regulating current in loads, such as in an array of independent pluralities of light emitting diodes (“LEDs”). An exemplary system comprises a multiplexer adapted to switch current to each independent string of LEDs; a first controller to maintain a substantially constant average current level to the plurality of LEDs; and a second controller to modulate a current amplitude and duration of time division multiplexing for each independent string of LEDs. Another aspect of the system provides for modulating the on time for switching current to maintain a substantially constant average current level and to respond and converge quickly to changing current reference levels.